EP0591872B1 - Continuously variable speed drive, particularly for two-wheeled vehicles - Google Patents

Continuously variable speed drive, particularly for two-wheeled vehicles Download PDF

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Publication number
EP0591872B1
EP0591872B1 EP93115922A EP93115922A EP0591872B1 EP 0591872 B1 EP0591872 B1 EP 0591872B1 EP 93115922 A EP93115922 A EP 93115922A EP 93115922 A EP93115922 A EP 93115922A EP 0591872 B1 EP0591872 B1 EP 0591872B1
Authority
EP
European Patent Office
Prior art keywords
disk
pulley
variable
spring
speed drive
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP93115922A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0591872A1 (en
Inventor
Paolo Nesti
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Piaggio Veicoli Europei SpA
Original Assignee
Piaggio Veicoli Europei SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Piaggio Veicoli Europei SpA filed Critical Piaggio Veicoli Europei SpA
Publication of EP0591872A1 publication Critical patent/EP0591872A1/en
Application granted granted Critical
Publication of EP0591872B1 publication Critical patent/EP0591872B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/66—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings
    • F16H61/662—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings with endless flexible members
    • F16H61/66231—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings with endless flexible members controlling shifting exclusively as a function of speed
    • F16H61/66245—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings with endless flexible members controlling shifting exclusively as a function of speed using purely mechanical sensing or control means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62M—RIDER PROPULSION OF WHEELED VEHICLES OR SLEDGES; POWERED PROPULSION OF SLEDGES OR SINGLE-TRACK CYCLES; TRANSMISSIONS SPECIALLY ADAPTED FOR SUCH VEHICLES
    • B62M9/00—Transmissions characterised by use of an endless chain, belt, or the like
    • B62M9/04—Transmissions characterised by use of an endless chain, belt, or the like of changeable ratio
    • B62M9/06—Transmissions characterised by use of an endless chain, belt, or the like of changeable ratio using a single chain, belt, or the like

Definitions

  • the present invention relates to a variable-speed drive, particularly for two-wheeled vehicles.
  • variable-speed drive is of the type comprising a pair of pulleys about which is wound a continuous belt for transmitting motion from a drive pulley to a driven pulley.
  • Each pulley comprises a pair of conical disks, one of which is movable axially in relation to the other for adjusting the width of the race defined by the disks and so varying the radius of the belt about the pulley.
  • the movable disk of one of the pulleys is pushed by at least a spring towards the other disk on the same pulley; and the movable disk of the other pulley, normally the drive one, is pushed towards the other disk on the same pulley by the centrifugal force produced by the rotation of bodies torsionally integral with and movable radially in relation to the movable disk.
  • said bodies push the movable disk towards the other disk, thus increasing the belt radius on the drive pulley and reducing that of the driven pulley.
  • Variable-speed drives of the above type also comprise a centrifugal clutch downstream from the driven pulley.
  • variable-speed drive as defined before and comprising the features of the preamble of claim 1 is known for instance from FR-A-2 457 210.
  • the gear ratio (the ratio of the angular speed of the drive pulley to that of the driven pulley) or the speed of the vehicle varies, as a function of the angular speed of the drive pulley, according to a nonlinear law depending on the geometric characteristics of the drive, the bodies integral with the movable disk on the drive pulley, the elastic characteristics of the spring by which the movable disk on the driven pulley is pushed towards the other, and, finally, on the characteristics of the clutch downstream from the driven pulley.
  • variable-speed drives of the above type may fail to provide for varying the law governing the relationship between the gear ratio or the speed of the vehicle and the angular speed of the engine, and so enabling selection of the gear ratio 'oest suited to the operating conditions of the vehicle. Under certain conditions, in fact, the gear ratio may be so high as to prevent the full power of the engine from being exploited.
  • variable-speed drive particularly for two-wheeled vehicles, comprising the features as defined in claim 1.
  • variable-speed drive The design and operation of the variable-speed drive according to the present invention will be described by way of example with reference to the accompanying drawings, in which:
  • variable-speed drive comprises a pair of pulleys: a drive pulley 1 connected to a drive shaft 3; and a driven pulley 2 connected to a driven shaft 4 for transmitting motion to the vehicle wheels.
  • a known type of centrifugal clutch indicated as a whole by 5.
  • Each of pulleys 1, 2 comprises a substantially conical disk 6 fitted to respective shaft 3, 4; and a conical disk 7 movable axially towards disk 6.
  • Each pair of disks 6 and 7 defines a race 8 housing a continuous drive belt 9 with a substantially trapezoidal section.
  • Movable disk 7 of driven pulley 2 is pushed towards disk 6 on the same pulley by a spring 13
  • movable disk 7 of drive pulley 1 is pushed towards disk 6 on the same pulley by the centrifugal force produced by the rotation of bodies 14 torsionally integral with and movable radially in relation to movable disk 7.
  • Said bodies 14 conveniently consist of rollers movable inside radial grooves on disk 7 and resting on a substantially conical active surface 15. Rollers 14 also rest on a further conical disk 16 fixed axially in relation to shaft 3 and defining, with surface 15, a cavity increasing in width alongside an increase in radius.
  • Each of movable disks 7 is conveniently connectable to respective shaft 3, 4 via a splined coupling 17 or other similar member.
  • variable-speed drive comprises a device 18 for controlling displacement of movable disk 7 of drive pulley 1.
  • control device 18 provides for exerting on disk 7, as this moves towards disk 6, a predetermined force generated by elastic means 19 and of such a direction as to oppose displacement of disk 7 towards disk 6.
  • Device 18 may also be set to a number of configurations, in each of which it exerts a predetermined force on movable disk 7 as this moves towards disk 6.
  • Elastic means 19 comprise at least a spring 20, which exerts said predetermined force on movable disk 7 of pulley 1 via a transmission 21 connecting spring 20 to disk 7.
  • Device 18 also comprises means for varying the preload of spring 20 and so varying said predetermined force, said means comprising an actuator 22 for moving one end 23 of spring 20 by a predetermined amount, the other end 24 of spring 20 being connected to transmission 21.
  • Actuator 22 conveniently comprises an electric motor 25 powering a reduction gear 26 connected to end 23 of spring 20.
  • device 18 comprises a coil spring 20 (Fig.s 4 and 5) housed inside a bell-shaped body 29 rotating inside a housing 30 integral with the casing of the variable-speed drive; and a shaft 31 coaxial with body 29 and rotating in housing 30.
  • End 32 of shaft 31 is inserted inside body 29, and spring 20 presents one end 24 fitted to a projection 33 of body 29 (Fig.5), and the other end 23 fitted inside a cavity on end 32 of shaft 31, as shown in Fig.5.
  • Shaft 31 rotates on a pin 34 (Fig.4) forming part of a casing 35 integral with the casing of the variable-speed drive and to which housing 30 is fitted by means of screws 36.
  • Shaft 31 is fitted integral with a helical gear 37 meshing with a worm 38 to which motion is transmitted by reduction gear 26 controlled by electric motor 25.
  • reduction gear 26 is irreversible, so that the torque exerted by electric motor 25 on worm 38 rotates helical gear 37 and consequently shaft 31, whereas the torque exerted on shaft 31 cannot rotate worm 38.
  • Transmission 21 comprises a flexible cable 42 (Fig.1) running inside a sheath 43.
  • a first end of cable 42 is connected via an oscillating lever 44 to a collar 45 for operating movable disk 7 of drive pulley 1; while the other end of cable 42 is connected to a projection 46 projecting from the outer surface of body 29, as shown in Fig.s 1 and 4.
  • Oscillating lever 44 is integral with a pin 47 (Fig.6) oscillating on a pair of bearings 48 on the casing of the variable-speed drive, and is connected to a fork 49 having a pair of arms engaging respective grooves on operating collar 45.
  • variable-speed drive as described above operates as follows.
  • Device 18 for controlling displacement of movable disk 7 of pulley 1 may be set to a number of configurations, each corresponding with a given preload of spring 20. Said preload is varied by exciting motor 25, which rotates worm 38 so as to rotate helical gear 37 integral with shaft 31. As a result, end 23 of spring 20 is rotated about the axis of shaft 31 so as to impart a given preload and so vary the torque applied on body 29 by the other end 24 of spring 20. This torque produces a pulling force on cable 42 with which corresponds a predetermined force on operating collar 45 in such a direction as to oppose displacement of disk 7 towards disk 6.
  • drive pulley 1 is set to a configuration wherein disk 7, for that particular preload, is at a maximum distance from disk 6, and the radius of belt 9 on drive pulley 1 is minimum.
  • a configuration is shown in Fig.2 wherein fork 49 is positioned with its arms substantially perpendicular to the axis of the pulley.
  • belt 9 on driven pulley 2 presents a maximum radius, by virtue of the force exerted by helical spring 13 providing for a minimum distance between disks 6 and 7.
  • centrifugal clutch 5 switches from the released configuration (when the engine was started) to the engaged configuration for transmitting the torque.
  • a first operating mode of the variable-speed drive corresponding with a minimum preload of spring 20, will be described with reference to the Fig.9 graphs showing the relationship between vehicle speed v and the angular speed ⁇ of drive shaft 3.
  • the clutch engagement phase commences and the vehicle starts moving.
  • the actual clutch engagement phase is shown by the almost horizontal portion 51 of curve a , during which phase sliding occurs between the mating surfaces of clutch 5 and the torque transmitted by the clutch increases gradually.
  • the gear ratio of the variable-speed drive increases so that the torque reaching clutch 5 decreases in relation to the initial value.
  • the clutch engagement phase terminates at the intersection of portion 51 and ray s indicating the gear ratio value ⁇ min for the minimum preload setting of spring 20 in said first operating mode.
  • angular speed ⁇ 1 at which rollers 14 start moving, disk 7 moves towards disk 6, thus increasing the radius of belt 9 on pulley 1 and reducing that of pulley 2.
  • the force exerted by spring 20 is transmitted via transmission 21 to movable disk 7 of pulley 1 so as to oppose displacement of disk 7.
  • lever 44 rotates slightly from the Fig.2 to the Fig.3 configuration accompanied by a corresponding rotation of body 29.
  • This operating phase is shown by portion 53 of curve a wherein the increase in vehicle speed v is produced by the increase in the gear ratio resulting from the variation in the radius of belt 9 on the drive and driven pulleys.
  • the maximum belt radius on pulley 1 corresponds with the end point of portion 53 on ray s'' indicating the maximum gear ratio ⁇ max .
  • vehicle speed v increases linearly alongside ⁇ , as shown by portions 54 and 55 of curve a , by virtue of the variable-speed drive now being set to gear ratio ⁇ max .
  • the preload of spring 20 need simply be increased by appropriately exciting electric motor 25. This results in an increase in the torque generated elastically on body 29, and consequently in the force exerted on and opposing displacement of disk 7 towards disk 6, so that a given axial position of disk 7 in relation to disk 6 corresponds with a higher angular speed ⁇ as compared with the same position in the first operating mode.
  • a second operating mode corresponding with a maximum preload of spring 20, will be described with reference to curve b in Fig.9, which, while presenting the same operating phases and form as curve a , is located substantially higher, indicating that a given vehicle speed v is achieved at a higher angular speed ⁇ of drive shaft 3.
  • the clutch 5 engagement phase commences at a higher angular speed ⁇ 0, as compared with the previous value ⁇ 0, by virtue of the torque on driven pulley 2 to be transmitted by clutch 5 being higher as a consequence of the minimum gear ratio provided for by the variable-speed drive with a maximum preload of spring 20 being lower than that provided for in the first operating mode.
  • the clutch engagement phase thus terminates at the intersection of portion 51' and ray s' indicating the new minimum gear ratio value ⁇ min , and is followed by portion 52' wherein vehicle speed v increases in proportion to angular speed ⁇ .
  • the variation in the gear ratio commences at a higher angular speed ⁇ 1, than that ( ⁇ 1) of the first operating mode, and, upon the variable-speed drive reaching gear ratio ⁇ max indicated by ray s", vehicle speed v increases linearly alongside angular speed ⁇ as shown by portion 55.
  • device 18 is so set as to provide for a higher preload of spring 20 corresponding with one of the higher curves c in Fig.9.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Transmissions By Endless Flexible Members (AREA)
  • Control Of Transmission Device (AREA)
  • Structure Of Transmissions (AREA)
EP93115922A 1992-10-05 1993-10-01 Continuously variable speed drive, particularly for two-wheeled vehicles Expired - Lifetime EP0591872B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITTO920804 1992-10-05
ITTO920804A IT1256957B (it) 1992-10-05 1992-10-05 Variatore continuo di velocita', in particolare per un veicolo a due ruote.

Publications (2)

Publication Number Publication Date
EP0591872A1 EP0591872A1 (en) 1994-04-13
EP0591872B1 true EP0591872B1 (en) 1996-05-01

Family

ID=11410758

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93115922A Expired - Lifetime EP0591872B1 (en) 1992-10-05 1993-10-01 Continuously variable speed drive, particularly for two-wheeled vehicles

Country Status (6)

Country Link
EP (1) EP0591872B1 (it)
AT (1) ATE137571T1 (it)
DE (1) DE69302455T2 (it)
ES (1) ES2086172T3 (it)
IT (1) IT1256957B (it)
TW (1) TW206194B (it)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19922619A1 (de) * 1999-05-17 2000-12-28 Uli Sommer Stufenloses Kegelradgetriebe für Verbrennungsmotoren
WO2010094181A1 (zh) * 2009-02-18 2010-08-26 Wu Xichun 无级变速器的控制方法及控制装置

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20010106046A (ko) * 2000-05-20 2001-11-29 김순곤 자전거용 무단변속기
DE10051931A1 (de) * 2000-10-19 2001-07-12 Holger Heuermann Anbtriebs- und Schaltungsvorrichtung für Fahrräder
DE102006009615A1 (de) * 2006-03-02 2007-09-06 Efim Avruckij Fahrradsantrieb mit automatischem Variator
CN105905229A (zh) * 2016-06-29 2016-08-31 麦志成 一种无级变速自行车
DE202019004758U1 (de) * 2019-11-22 2019-12-04 Scc Fahrzeugtechnik Gmbh Stufenlos schaltbarer Riemenantrieb oder Antriebseinheit

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1450681B1 (de) * 1964-01-24 1970-03-19 Louis Henri Denis Marie Ballu Keilriemen-Differentialwechselgetriebe
JPS55155951A (en) * 1979-05-23 1980-12-04 Honda Motor Co Ltd Power transmission in motorcycle

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19922619A1 (de) * 1999-05-17 2000-12-28 Uli Sommer Stufenloses Kegelradgetriebe für Verbrennungsmotoren
DE19922619C2 (de) * 1999-05-17 2001-12-06 Uli Sommer Kegelscheibenumschlingungsgetriebe für einen Dieselmotor
WO2010094181A1 (zh) * 2009-02-18 2010-08-26 Wu Xichun 无级变速器的控制方法及控制装置

Also Published As

Publication number Publication date
EP0591872A1 (en) 1994-04-13
DE69302455T2 (de) 1996-11-28
DE69302455D1 (de) 1996-06-05
TW206194B (en) 1993-05-21
ITTO920804A0 (it) 1992-10-05
ITTO920804A1 (it) 1994-04-05
ES2086172T3 (es) 1996-06-16
IT1256957B (it) 1995-12-27
ATE137571T1 (de) 1996-05-15

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